chore: cargo fmt across workspace; add analytics domain to CSP

- Apply cargo fmt to solitaire_engine, solitaire_server formatting.
- solitaire_server/src/lib.rs: add https://analytics.aleshym.co to
  script-src, img-src, and connect-src so the analytics beacon loads
  without a CSP violation.
- docs and README updates.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_engine/src/audio_plugin.rs

@@ -373,9 +373,7 @@ fn play_on_draw(
         // When the stock pile is empty the draw action recycles the waste pile
         // back to stock. Play the flip sound at half volume to give audible
         // feedback that distinguishes a recycle from a normal draw.
-        let stock_len = game
-            .as_ref()
-            .map_or(1, |g| g.0.stock_cards().len()); // default > 0 → normal draw sound
+        let stock_len = game.as_ref().map_or(1, |g| g.0.stock_cards().len()); // default > 0 → normal draw sound
 
         if is_recycle(stock_len) {
             let mut data = lib.flip.clone();